p.1 

RCRA Box 1883 

Prepped by Ollie Stewart 

Document Number: 

39) ll-B-200 

Docket Number: 

A-90-19 

Printed 12/3/2008 10:42:12 AM Sheet 39 of 171 
P.2 

A-90-19 

ll-B-200 

MEMORANDUM 

TO: Process Vents Docket A-90-19 

FROM: 

DATE: 

Wanda Floyd 

December 1991 

SUBJECT: HON NESHAP: Industry Characteristics/ Vinylidene Chloride 

Attached is a product-process summary (PPS) for the production of Vinylidene Chloride 

via dehydrochlorination of 1,1,2-trichloroethane. This PPS was developed as part of the 

Industrial Profile project in support of the Hazardous Organic NESHAP (HON) 

regulatory program. Information in this PPS is used as a basis for emissions and cost 

impact estimates for the HON program. 

Listed below are the key references used in developing the attached PPS. 

Kirk-Othmer. Encyclopedia of Chemical Technology. 3rd edition. John Wiley & Sons, 

New York, 1985. pp. 764,766. 

EPA-450/3-80-028c. Organic Chemical Manufacturing vol. 8: Selected Processes. 

December, 1980. pp. II-6, 11-15 to 111-17, IV-15, IV-19 to IV-20, V-7. 

Weissermel, Klaus and Arpe, Hans-Jurgen. Industrial Organic Chemistry. Verlag Chemie, 

New York, 1978. p. 197. 

Austin, George T. Shreve's Chemical Process Industries. 5th edition. McGraw-Hill Book 

Company, New York, 1984. pp. 660-661. 

1989 Directory of Chemical Producers USA. SRI International, California, 1989. p. 1058. 

The Corresponding .Quality. Ass^aase 

x Doeyment is Docket Item , 

A-90-19 

ll-B-252 
P.3 

Preparer: 

Date: t/il/to 

Reviewer: 

ADMINISTRATIVE NOTES 

Pr<jdntt-Proce$$ Cttfc 

Hours spent on thi s PPS 1AX 

P-P Name DeA^Jroc/i/ar>.»«/he» _ / / /, i- - (fsXtzJi/ose/rtAaA,* 

Incomplete Items (parts of 

form you cannot complete) 

(line # and description) Date Cleared Initials 

Chemicals missing CAS numbers 

Plant with Citv but no County (plant name, city, state) 
P.4 

Preparer: 

Date: $/tf/to Z 

Reviewer: 

CheBical Name 

PRODUCT-PROCESS SUMMARY (PPS) 

Alternative Cheutfcal 

CAS? I I f 35 + 

U- Z)A AJtrO£ /Aj, Ujt* 

Karea Fftfllr CKeiRfctT Nun&er lJ> 

CHEMICAI SPECIFIC INFORMATION 

1.0 U.S. Production Ref # / / . Pg # f'fi. Ref Year JJP f 

(Indicate the same reference information for any answers below from a 

different reference) 

1.1 \ URfIF W prtKfUCtfOR (Circle oneKjimions of koNor millions of gallons 

1.2 U, S> Capacity I?- 0- /_^_^_*/ 

1.3 M, S. tapasny Utilisation* '.& 

{*» $TEN^N ^ <&& 

ffflpttft* t^<£s£: 

reports ,~~/~<r 

Product Price 

1,4 

1.5 

I>$ 

1.7 

1.7.1 Average Price w-^-t-r 

1.7.2 tffttts af ^mj^fWT^Q^irm^r S/gallon 

1.8 Comments 
P.5 

1

 2.0 ' Chemical End-Use Ref # _____• Pg * ___£2_ , Ref Year __f '** 

U_Sfi Percent 

P&by pro 2 e *~C-
3.0 U.S. Producers Ref # _____ _ Pg # _J_____ , Ref Year ^ ^ 

ldteM|s^9 f Pr^lMi&fCPl e we) ^lto7is^rjcg^_or—millio n of galops 

3.2 Name, Location, and Capacity 

Location, 

Process Used 

(use P-P #) 

fft-

<Av»ej L/l 

L*At CA^r/ey 6 & 

Total Capacity /12 
P.7 

PRODUCT-PROCESS SPECIFIC INFORMATION 

4.0 Potential Product-Processes (P-P) Ref # _______ Pg I IZ? ~& 

Commercially % Nat'l 

_ _ £ Viable (v/nl Capacity 

P-P 1 JeJ.yJrtci/*'r~S:*» ^ (. A 2 - A;**/-,*,./^ T /<*> 

P-P 2 

P-P 3 

P-P 4 ; 

P-P 5 

P-P 6 

4.1 Documentation of P-Ps Excluded 

P-P not 

Commercially Viable Reasons 

4.2, t*m*ti describes* , . . . t ,. t , 

in this m ' * XffyJscc^/^.^Sr** *t i'. T. ~ f *<*//.*e <*./<*-<. 
Ref # 

A1r Oxidation Reaction 

Oxidation Reaction 

Alkylation Reaction 

Carbonylation Reaction 

Halogenation Reaction 

Condensation Reaction 

Dehydrogenat1on Reaction 

3feh7droBaJ'-6genation Ri 

Esterification Reaction 

Hydrogenation Reaction 

Hydrohalogenation Reaction 

Hydroformylation Reaction 

Hydrolysis Reaction 

Nitration Reaction 

Oxyacetylation Reaction 

Oxyhalogenation Reaction 

Sulfonation Reaction 

Catalytic Reformation 

Hydrodimerization Reaction 

tf . Pg # Zzr-Af 

Generic Reaction 

4.4 Explain how you selected the reaction type in line 4.3. 
P.9 

4.5 Written Description 

In the left margin, indicate references and page numbers throughout written description. 

r</'VM 

fAct se**fXaA ;$ c*ss/c/ <nA~ ; yfy, / a 'A / ^ 

of aicu^ <** ^ „;& « re^'oeA, J./^Z fr * ,* ^ ^ 

A/a ttf so/*fr«. 

e*~7P e<~ «<c.^_ 
P.10 

*"•' • i liftifliilfti 1'ililMM 

111-15 

VINYLIDENE CHLORIDE 

Vinylidene chloride is produced domestically by the dehydrochlorination of 

1,1,2-trichloroethane as represented by the following reaction:8'

13'14 

CH2CI-CHCI2 + 

(1,1,2-trichloroethane) 

NaOH 

(sodium 

hydroxide) 

CH2=CC12 

(vinylidene 

chloride) 

NaCl H,0 

(sodium (water) 

chloride) 

The reaction is carried out in the liquid phase at a temperature of about 100°C, 

with a relatively dilute (5 to 10 wt %) sodium hydroxide solution. Product yields 

are believed to range from 85 to 90%.13 

Figure III-5 represents a flow diagram for a process in which vinylidene chloride 

is produced from 1,1,2-trichloroethane.8'

13'14 Concentrated sodium hydroxide 

solution (stream 1) is diluted with water (stream 2) to 5 to 10% concentration 

and combined with 1,1,2-trichloroethane feed (stream 3), with unreacted 1,1,2-trichloroethane (stream 16) recycled from the distillation section of the process, 

and with a recycled sodium hydroxide—salt solution (stream 8). The combined 

feed stream (4) is further mixed to provide dispersal of the insoluble organic 

phase in the aqueous phase before it is fed to the dehydrochlorination reactor. 

The dehydrochlorination reactor is continuously purged with nitrogen (stream 5) 

to prevent the accumulation of monochloroacetylene impurity in the vinylidene 

chloride product, a step that results in a process emission source (vent A). 

The two-phase reactor effluent (stream 6) is separated into two streams. The 

aqueous phase (stream 7), composed of a sodium hydroxide—salt solution saturated 

with organic compounds, is split. One fraction (stream 8) is recycled to the 

dehydrochlorination reactor. The other fraction (stream 9) is combined with 

the bottom stream (14) from the drying column and fed to the stripping column, 

where steam (10) is introduced countercurrently to strip most of the dissolved 

organics from the aqueous phase. The organics (stream 11) are removed overhead 

and are combined with the organic phase (stream 12) from the phase separator as 

feed to the drying column. The stripped aqueous phase is removed as the bottom 

stream (source F) and discharged to the wastewater treatment system. 
P.11 

• II M lir , ^ i a ^ | BiiM^

1 | M1MMMMMM | ^ MMM , M

^

MMMI I 

IH-17 

The drying column bottom stream (14), which contains most of the residual water, 

is recycled to the stripping column. The drying-column overhead stream (15) 

passes to the finishing column, where the overhead stream (16), composed primarily 

of unreacted 1,1,2-trichloroethane, is removed and recycled to the dehydrochlorination reactor. The refined vinylidene chloride product is removed as the bottom 

stream (17) and transferred to storage in pressurized tanks. From storage the 

vinylidene chloride may be transferred by pipeline for internal use (stream 18) 

or loaded (stream 19) into tank trucks and tank cars for off-site consumption. 

The dehydrochlorination reactor purge vent (A) and the distillation column vents, 

(B) which release primarily noncondensable gases, are sources of process emissions. 

Storage emissions (vent C) are the emissions from storage of 1,1,2-trichloroethane. 

Handling emissions (vent D) result from the loading of vinylidene chloride into 

tank trucks and railroad tank cars. With pressurized tanks used for vinylidene 

chloride storage no significant emissions from product storage occur. 

Fugitive emissions (E) occur when leaks develop in valves or in pump or compressor 

seals. When process pressures are higher than the cooling water pressure, VOC 

can leak into the cooling water and escape as fugitive emissions from the cooling 

tower. 

Secondary emissions can occur when wastewater discharged from the stripping 

column (source F) is sent to a wastewater treatment system and the contained 

VOC are desorbed. 
P.12 

5.0 Process Flow Diagram (attach at end of package) 

5.1 Flow Diagram Reference: Ref # /9 Pg # f& ~ /^ 

5.2 Comments on Flow Diagram 

5.3 Process 

Component Types 

Distillation Columns 

Absorbers 

Strippers 

Reactors 

Condensers 

Vaporizers 

Others 

*%tfr $y*f/*> 

Ap^. 

Ref # /I Pg # **-/* 

wffltim ***** ww$m. 

shownJ 

.A. / 

Total Number J*_"7 
P.13 

6.0 Chemical Data 

6.1 Balanced Chemical Reactions 

c/t^ a- cyc/z. + faou 

(//l/l' ('A A fare e /**** J /}«/.'-— 

AuA-t/rr'/e J 

Ref * /? Pg # &-<f 

(i/'Aj/yc/e^-e 

cA-icrXei£J 

6.2 Chemical Tree Ref # ____L_ , Pg # & -/J" 

I, t,L- O.'ckL'otjU^ ^ i/S«j/;*/e~-t tl/o+Se/* 
P.14 

6.4 Stoichiometry Ref f 

., Pg # 

Show calculations and assumptions and then summarize 1n table on next 

page. 

t/'/l-- {s/ck/o^c e ^ A^ 

/^ 7/ j .OfO ty <// ^ 

%U-'(*— ^/<>AA 

[Jo/li 
P.15 

's:ri si §gg?$ (cont t ttued) 

H .fflHIIBBf 

6.4.1 Product 

6.4.2 Raw MateriaUs) 

#1 £,y/<u. LJ'c/t/e 

#3 

#4 

#5 

6.4.3 Co-Products 

#1 

n 

n 

#4 

#5 

6.4.4 Bv-Products 

#1 %// W £t>/i't£e 

n 

#3 

#4 

#5 

Ua^i 

6.4.5 Intermediates 

#1 

#2 

fit* 73 L iA 

/. •>?? 

Ac 
P.16 

6.4 Stoichiometry Conversion Factors 

a» •Rf91 « -fO 

b) *p|p«T*&t&r for c^prm^m 

c) c&nverston facto* tut to-?ttmci\9i ; 

d) Coaversiap Faet&r foi* Cs-Pfrxfuef, 13 

e) Conversion FaetoF f&* Co-PYodMrf* 

• A S SSS S % S S •.-. S S<SSSS\>s4>- ^^^^^^^B^ M 

f) Conversion Factor Comments 
P.17 

7.0 Process Vent Emission Sources 

7.1 A^^Mtj|rl€|ssjent; emissions? ____ _ (Y/N) 

7*2 A1f q^ptlos vent emissions? ty (Y/N) Ref # , Pg # 

7.3 Comments Ref # , Pg # 

7.4 Reactor vent emissions? /iL (Y/N) Ref # , pg # 

7.5 Comments Ref # , Pg # _ 
P.18 

v p t elf ssfons? / (Y/N) Ref # ., Pg * 

lef^cf no^Je^ oiiJe' *dta*~ 

/ 

O 

Ref # 

., Pg * 
8.2.1 Product 

U/ruj/ 'ae^-e^ / £ /as f*/? 

8.2.2 Co-Products 

7XJX¥ 

P.19 

8.0 Transfer Emission Sources 

8

-1 ^ vgp/C^I¥o(fyct $ Transferred 

8.2 What mterfals are transferred? 

Ref # ., Pg # 

,K (Y/N) 

CAS Nuiber 

8.3 Comments Ref # ., Pg # 
P.20 

9.0 Storage Emission Sources Ref # , Pg § 

$.1 ArTippraTs stored? IY (Y/N) 

9/. 2 WhatJmaterials are stored? 

9.2.3 Raw Materials 

9.2.4 Intermediates 

Storage Service 

CAS I Type 

9.2.1 Product yf^ ^ 

IZ/r^/^c^c e/>6>r<rc/e ^ ^ ~ fa'rAV' fr*/- for 

9.2.2 Co-Products 

fDi/>\tr» Ay/?cftit I I/O?? 2* %**-*+?, fteS. 

9.4 Comments 
P.21 

10.0. Wastewater Emission Sources 

10.2 Describe wastewater 

Ref # ., Pg # 

(Y/N) 

Stream Equipment Component 

Number Producing Wastewater Comments on flow 

#1 

#2 

#3 

s i^'/pf -'—\ 6*1— 

10.3 Stream Composition 

(provide only if readily available) 

Stream #1 

Ref # 

Steam #2 

., Pg # 

Organics Organics 

HAPs HAPs 

Water 

Other 

Water 

Other 
P.22 

Stream #3 

Organics _ 

HAPs 

Water 

Other 

10.4 Comments Ref # 

., Pg # 
11 

© 

•© 

. _ . 

3eo-| 

\,\,l- TKICHLOR.O-

& . 

couce.uTBATto 

IJOOH «XUT ^ 

D6HYDB 

CULCRJUAPOU 

REACTOR. 

H 2 0 

<£ 

~§~: 

o 

PHA"bE ,_- ^ 

SEpARATCCj 

S 

<a 

<£ 

*^£ " 

^ > 

COL.UMU COLUt^Nl 

sreipp>w<3 

COLUWU 

pCOkA 

F>UVSH\MG| 

COLUM KJ 

A$> STEAM 

'© 

EKAIt.^lOKJ'i 

OV£»£.ALJPLAUT ' 

© 

V»UVLIOEU 6 

CHL.CQ.lCt. 

TO 

ue-ta.*. M 

M 

M 

I 

M 

Fig. III-5 . Flow Diagram for Vinylidene Chloride from 1,1,2-Trichloroethane 
' 

» 

vvERA 

United States Office of Air Quality EPA-450/3-80-028c 

Environmental Protection Planning and Standards December 1980 

Agency Research Triangle Park NC 27711 

Air 

Organic Chemical 

Manufacturing 

Volume 8: Selected 

Processes 

PROPERTY Of 

EPA LIBRARY 

RTP,.NO 
Table II-2. Production Capacity for 1,1,1-Trichloroethane, 

Perchloroethylene, Trichloroethylene, and Vinylidene Chloride 

1979 Capacity (Mg/yr) 

Company Location 1,1,1-Tricliloroethanc Perchloroethylene Trichloroethylene Vinylidene Chloride 

Diamond Shamrock 

Dow 

Du Pont 

Ethyl 

PPG 

Stauffer 

Vulcan 

Deer Park, TX 

Freeport, TX 

Pittsburg, CA 

Plaquemine, LA 

Corpus Christi, TX 

Baton Rouge, LA 

Lake Charles, LA 

Louisville, Kr 

Geismar, LA 

Wichita, KS 

Total 

204,000 

136,000 

159,000 

90,000 

589,000 

75,000 

68,000 

18,000 

54,000 

73,000 

23,000 

91,000 

32,000 

68,000 

23.000 

525,000 

b 

68 

20 

91 

000 

' 

000 

000 

23 

c 

,000—45 

88 oood 

000 

179,000 

See ref 2. 

23,000-Mg/yr capacity unit placed on standby in early 1978 (ref 2). 

Capacity data not available. 

Includes 23,000-Mg/yr expansion completed in 1978 (ref 9). Most of this capacity (88,000 Mg/yr) was placed on stand-by with the shutdown 

of PPG's vinylidene chloride—based 1,1,1-trichloroethane process. 

I 

__r 
mmmmm 

111-15 

D. VINYLIDENE CHLORIDE 

Vinylidene chloride is produced domestically by the dehydrochlorination of 

1,1,2-trichloroethane as represented by the following reaction:8'

13'14 

CH2CI-CHCI2 + NaOH 

(1,1,2-trichloroethane) (sodium 

hydroxide) 

CH2=CC12 

(vinylidene 

chloride) 

NaCl + H20 

(sodium (water) 

chloride) 

The reaction is carried out in the liquid phase at a temperature of about 100°C, 

with a relatively dilute (5 to 10 wt %) sodium hydroxide solution. Product yields 

are believed to range from 85 to 90%.1 3 

Figure III-5 represents a flow diagram for a process in which vinylidene chloride 

is produced from 1,1,2-trichloroethane.8'

13'14 Concentrated sodium hydroxide 

solution (stream 1) is diluted with water (stream 2) to 5 to 10% concentration 

and combined with 1,1,2-trichloroethane feed (stream 3), with unreacted 1,1,2-trichloroethane (stream 16) recycled from the distillation section of the process, 

and with a recycled sodium hydroxide—salt solution (stream 8). The combined 

feed stream (4) is further mixed to provide dispersal of the insoluble organic 

phase in the aqueous phase before it is fed to the dehydrochlorination reactor. 

The dehydrochlorination reactor is continuously purged with nitrogen (stream 5) 

to prevent the accumulation of monochloroacetylene impurity in the vinylidene 

chloride product, a step that results in a process emission source (vent A) . 

The two-phase reactor effluent (stream 6) is separated into two streams. The 

aqueous phase (stream 7), composed of a sodium hydroxide—salt solution saturated 

with organic compounds, is split. One fraction (stream 8) is recycled to the 

dehydrochlorination reactor. The other fraction (stream 9) is combined with 

the bottom stream (14) from the drying column and fed to the stripping column, 

where steam (10) is introduced countercurrently to strip most of the dissolved 

organics from the aqueous phase. The organics (stream 11) are removed overhead 

and are combined with the organic phase (stream 12) from the phase separator as 

feed to the drying column. The stripped aqueous phase is removed as the bottom 

stream (source F) and discharged to the wastewater treatment system. 

•WML. !• .1 I WJHU M s—'I 
T O 

© 

»® 

jS\ DGHYOeO-j 

\,I,Z - TBVCHUOE.OerwAME vroeAGE 

£. 

COUC5.UTKATSO 

UOOH *>OLLrr^ 

eEACTOBH 2 0 

<£ 

«F~: 

0 

PHAS E ^—p , 

SCpARATTC y 

<S 

< & 

<& 

* ~ ^ 

"»„ t », 

^ > 

^ 

COLU M U CCrt-UMNI 

STEiPpiMG , 

COLUMK J 

peo»*/\ 

rMM\£>H\U5 

COLU M M 

" ^ 

STEA M 

3> 

'© 

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OVE.VE.A.LJPLAUT ' 

© 

vt>-JVLioeue 

CHLCW.ICS. 

s-fO(tAG,e 

TO 

Uata*» w 

I 

M 

Fig. III-5. Flow Diagram for Vinylidene Chloride from 1,1,2-Trichloroethane 
P.28 

111-17 

The drying column bottom stream (14), which contains most of the residual water, 

is recycled to the stripping column. The drying-column overhead stream (15) 

passes to the finishing column, where the overhead stream (16), composed primarily 

of unreacted 1,1,2-trichloroethane, is removed and recycled to the dehydrochlorination reactor. The refined vinylidene chloride product is removed as the bottom 

stream (17) and transferred to storage in pressurized tanks. From storage the 

vinylidene chloride may be transferred by pipeline for internal use (stream 18) 

or loaded (stream 19) into tank trucks and tank cars for off-site consumption. 

The dehydrochlorination reactor purge vent (A) and the distillation column vents, 

(B) which release primarily noncondensable gases, are sources of process emissions. 

Storage emissions (vent C) are the emissions from storage of 1,1,2-trichloroethane. 

Handling emissions (vent D) result from the loading of vinylidene chloride into 

tank trucks and railroad tank cars. With pressurized tanks used for vinylidene 

chloride storage no significant emissions from product storage occur. 

Fugitive emissions (E) occur when leaks develop in valves or in pump or compressor 

seals. When process pressures are higher than the cooling water pressure, VOC 

can leak into the cooling water and escape as fugitive emissions from the cooling 

tower. 

Secondary emissions can occur when wastewater discharged from the stripping 

column (source F) is sent to a wastewater treatment system and the contained 

VOC are desorbed. 

unu •- ..——J—9mmILII ll m lip—UI"*fB~g~«~WW~WP 
i.1j.».takL_S.. ..tv.*.—_*M*-i 

IV-15 

does not include storage, handling, fugitive, or secondary emissions. The composition 

and flow of the uncontrolled emissions in the gas from the reactor vent (A), in 

the gas from the drying column vent (B), and in the gas from the distillation 

vents (C) are given in Tables IV-10—12 respectively.4'

16'17 

D. VINYLIDENE CHLORIDE 

The process flow diagram (Fig. III-5) for the production of vinylidene chloride 

from 1,1,2-trichloroethane represents the processes used by Dow Chemical Company5'

18 

and PPG Industries, currently the only domestic producers of vinylidene chloride.2'

3 

Emissions from the reactor vent (A) are composed of vinylidene chloride, monochloroacetylene, and nitrogen and result from the purging of the reactor to prevent 

the accumulation of monochloroacetylene in the liquid vinylidene chloride product. 

An estimate of the reactor vent gas composition is given in Table IV-13. 

An estimate of the composition of the distillation column vent (B), the other 

source of process emissions, is given in Table IV-14. The estimated quantities 

of emissions from both sources (vents A and B) are based on information from 

two plants6'

18 and the total is given in Table IV-7. 

I 

•mmptwrnm 
P.30 

IV-19 

n. KI - TV ^ Estimated Composition of Vent Gas from 

^RLcror'sectioro f a Vinylidene Chloride Planta 

Component 

Composition 

(wt %) 

Vinylidene chloride 

Monochloroacetylene 

Nitrogen 

56 

8 

36 

Emission Ratio 

(g/kg)b 

6.2 

0.9 

4.0 

aSee refs 3, 4, and 5. 

b

g of emissions per kg of product produced. 

i 
IV-20 

Table IV-14. Estimated Composition of Distillation 

Vent Gas from a Vinylidene Chloride Plant3 

Component 

Vinylidene chloride 

Nitrogen 

aSee ref 18. 

Composition 

(wt %) 

50 

50 

Emission Ratio 

(g/kg)b 

0.7 

0.7 

g of emissions per kg of product produced. 
V-7 

Table V-4. Estimates of Controlled VOC Emissions from a 

Vinylidene Chloride Process3 

Source 

Reactor vent 

Distillation vent 

Total 

Uncontrolled VOC 

Emission Ratio 

(g/kg)b 

7.1 

0.7 

7.8 

Control Device 

Incineration 

Aqueous scrubber 

VOC Emission 

Reduction 

(%) 

98 

90 

Controlled VOC 

Emission Ratio 

(g/kg)b 

0.14 

0.07 

0.21 

See refs 2 and 8. 

g of emissions per kg of vinylidene chloride produced. 

^P—«———«M— < 
P.33 

' » 

"io! 

ST- 7^p - 0O?39/i/e 

\<f&9 C.X. ^ 

198 9 DIRECTORY OF 

CHEMICAL PRODUCERS 

UNITED STATES OF AMERICA 

Information in this Directory is for the sole 

and private use of sponsors of tha 

Directory of Chemical Producers Program. 

QAP'J M * »P-?AR Y 

V 
fclil 

333 RAVENSWOOO AVENUE 

MENLO PARK. CALIFORNIA 94025 

(415)859-3627 

FAX: (415)326-5512 

TWX: 910-373-2046 

TELEX: 334486 

Copyright O 1989 SRI rmamational. Unauthorized use or reproduction of all or any part of this document <s 

prohibited. Printed in USA 
1989 DIRECTORY OF CHEMICAL PRODUCERS 

UNITED STATES PRODUCTS 

Vmyl aeatata vinyl cMorida ethylene terpolymer rtsins 

(See: Plastics and Resins) 

Vinyiacetonitrile (See: Allyl cyanide) 

Vinylbenzene (See: Styrene) 

p-Vinylbanzenesulfonic acid, sodium salt (See: Sodium fistyrene sulfonate) 

Vinyl benzyl chloride monomer 

Dow Chemical U.SA Midland, Michigan 

Vinyl bromide monomer 

Ethyl Corporation 

Cnemicals Group Magnolia, Arkansas 

Vinyl butyl ether (See: n-Butyl vinyl ether) 

N-Vinylcarbazole 

Polysciences, Inc. Warrington, Pennsylvania 

Vinylcarbinol (See: Allyl alcohol) 

Vinyl chloride-ethylerie copolymer resins (See: Ethylenevinyl chloride copolymer resins under Plastics and Resins) 

Vinyl chloride monomer (Chloroethylene) (VCM) 

Borden Chemicals and Plastics 

Partnership 

Dow Chemical U.SA 

Formosa Plastics Corporation U.SA 

Georgia Gulf Corporation 

The BFGoodrich Company 

BFGoodrich Chemical Group 

Occidental Petroleum Corporation 

Occidental Chemical Corporation, 

subsidiary 

Plastics & Polymers Division 

PVC Resins and Fabricated 

Products Group 

PPG Industries, Inc 

Chemicals Group 

Vista Chemical Company 

Geismar, Louisiana 

Oyster Creek, Texas 

Plaquemine, Louisiana 

Baton Rouge, Louisiana 

Point Comfort, Texas 

Plaquemine, Louisiana 

Calvert City. Kentucky 

La Porte, Texas 

Deer Park, Texas 

Lake Charles, Louisiana 

Lake Charles, Louisiana 

TOTAL 

Annual Capacity 

(Millions of Pounds) 

800 

700 

10S0 

400 

S80 

1Q00 

1000 

1300 

10S0 

650 

720 

9,250 

Process 

Ethylene-oxychlori nation 

Ethylene-oxychlorination 

Ethylene-oxychlorination 

Ethylene-oxychlorination 

Ethylene 

Ethylene-oxychlorination 

Ethylene-oxychlorination 

Source: SRI International estimates as of January 1, 1989. 

Vinyl 2-chloroethyi ether 

Interchem, Inc. 

Alcolac subsidiary Sedalia, Missouri 

Vinyl chloroformate 

PCR Inc. Gainesville, Florida 

Vinyl cyanide (See: Acrylonitrile) 

4-Vinyl- 1 -cyclohexene (Butadiene dimer) (4-Ethenyl-1 -

cyclohexene) (1,2,3,6-Tetrahydrostyrene) 

Union Carbide Corporation 

Chemicals and Plastics Business 

Group 

Specialty Chemicals Division Institute, West Virginia 

Vinylene carbonate 

Polysciences, Inc Warrington, Pennsylvania 

Vinylethylene (See: 1,3-Butadiene) 

Vinyl ethyl ether (See: Ethyl vinyl ether) 

Vinyl ferrocene 

. Parish Chemical Company 

Vinyl fluoride (Fluoroethylene) 

E. I. du Pont de Nemours & Company, 

Inc 

Chemicals and Pigments 

Department 

Fraon* Products Division 

Vlnytformic acid (See: Acrylic acid) 

Orem, Utah 

Louisville, Kentucky 

Vinylformic acid esters (See: Acrylate esters) 

/Vinylidene chloride monomer (1,1 -Dichloroethylene) 

/ Dow Chemical U.SA Freeport, Texas 

[ PPG Industries, Inc 

V Chemicals Group Lake Charles. Louisiana 

Vinylidene fluoride (See: 1,1-Difluoroethylene) 

Vinyl isobutyl ether (See: Isobutyl vinyl ether) 

Vinyl methyl ether (See: Methyl vinyl ether) 

5-Vinyl norbomene (VBCH) 

Union Carbide Corporation 

Chemicals and Plastics Business 

Group ... . • 

Specialty Chemicals Division Institute, West Virginia 

Vinyl octadecyl ether (See: Octadecylvinyl ether) 

2-Vinytpyridine 

Reilly Industries, Inc 

4-Vinylpyridine 

Reilly Industries, Inc 

Indianapolis, Indiana 

Indianapolis, Indiana 

Vinyl pyridine latex (See: Styrene-butadiene-2-vinylpyridine 

latex under Elastomers) 

1-Vinyl-2-pyrrolidinone 

GAF Corporation 

GAF Cnemicals, subsidiary Calvert City. Kentucky 

1058 SRI International 
AL-W) 

Shreve's 

Chemical 

Process 

Industries 

GEORGE T. AUSTIN 

Professor Emeritus of Chemical Engineering 

Washington State University 

Fifth Edition 

McGraw-Hill Book Company 

New York St. Louis San Francisco Auckland Bogota Hamburg 

Johannesburg London Madrid Mexico Montreal New Delhi Panama 

Paris Sao Paulo Singapore Sydney Tokyo Toronto 

RADIAN LIBRARY 

RESEARCH TRIANGLE PARK. NC 
Library of Congress Cataloging in Publication Data 

Shreve, Randolph Norris, 1885-1975 

Shreve's Chemical process industries. 

Includes index. 

1. Chemistry, Technical. 

I. Austin, George T, 1914-

TP145.S5 1984 660.2 

ISBN 0-07-057147-3 

2. Chemical industry. 

II. Title. 

83-13629, 

Copyright © 1984, 1977, 1956 by McGraw-Hill, Inc. All rights reserved. 

Copyright 1945 by McGraw-Hill. Inc. All rights reserved. Printed in 

the United States of America. Except as permitted under the United 

States Copyright Act of 1976, no part of this publication may be 

reproduced or distributed in any form or by any means, or stored in a 

data base or retrieval system, without the prior written permission of 

the publisher. 

34567890 DOC/DOC 89876 

ISBN Q-Q7-0S71M7-3 

The editors for this book were Joan Zseleczky and Rita Margolies, the designer was 

Jules Perlmutter. and the production supervisor was Thomas G. Kowalczvk. 

It was set in Caledonia by University Graphics. Inc. 

Printed and bound by R. R. Donnelley & Sons Company 

i~L*L 
660 Chap. 34 Plaatic Industries 

ticized by water and is completely soluble in an excess of water. Polyvinyl alcohol reacts with 

an aldehyde under the influence of heat and in the presence of an acid catalyst, such as 

sulfuric or hydrochloric acid, and the result is a typical acetal. Polyvinyl butyral is formed as 

follows: 

— CH —CH., —CHI " I 

0 

-CH.,— + C3H7CH0 

H 

0 

I 

H 

— CH — CH., — CH — CH2-

I " I 

0 — CH — 0 

The corresponding formal and acetal are: 

-CH — CH., — CH— CH2-

I I 

0 — CH — 0 

I 

H 

Formal 

-CH —CH2 —CH—CH2 — 

I I 

0—CH — 0 

I 

CH., 

Acetal 

In actual commercial production, the hydrolysis and condensation reactions are never carried 

to completion because it has been found that the presence of residual acetyl and hydroxyl 

groups gives the resins better properties. 

Polyvinyl butyral is usually extruded as a sheet for the interlayer for safety glass. Some 

polyvinyl acetals can be compression-molded at temperatures from 100 to 130°C and injection-molded at temperatures from 170 to 190°C. Polyvinyl formals can be molded by either 

compression or injection, depending upon the softening point. 

Vinylidene Resins. This class of resins was introduced in 1940 and is formed by the 

polymerization of the monomeric vinylidene chloride, CH2=CC12, or vinylidene fluoride. 

These .resins may be represented as: 

H Cl H Cl H Cl H Cl 

I I I I I I I I 

—C—C—C—C—C—C—C—C — 

I I I I I I I I 

H a H Cl H Cl H Cl 

or the monomer may be copolymerized with vinyl chloride to give a new product represented 

as: 

H a H Cl H Cl H Cl H Cl 

I I I I I I I I I I 

—C—C—C—C—C—C—C—C—C—C — 

I I .1 I I I I I I I 

H H H Cl H Cl H Cl H H 

The resins formed by copolymerization range from a flexible material having a softening 

point of about 70°C to a hard, thermoplastic solid with a softening point of 180°C. Their 

higher softening point indicates a greater degree of crystalline character. If the fibrous crystals are not oriented, the vinylidene chloride has a tensile strength of 55 MPa, which is an 

ordinary value. If the crystals are oriented by drawing, however, the tensile strength may be 

increased to about 410 MPa. These resins may be fabricated by compression or injection 

molding or 

accurate cc 

STYRENEI 

tion of eth\ 

polymeriza 

tion at mo' 

weight, wl 

catalysts si' 

ular weigh 

85°C in a 

The viscoi 

200°C, to • 

The extrucl 

with acrylo 

Another 

p-methyl si 

to produce 

ACHYLIC Hi 

acrylic acic 

merization 

or in solutic 

are increasi 

used becau: 

lent optical 

their excelh 

clamps. Em 

Alloying 

The properl 

polymers. T 

are not full; 

ylene oxide 

microscope, 

is much easi 

ones. 

One of tl 

adhere toge 

ing polymei 

compatibili: 

wMod. Ph 

3IA Better 

MDuBois a 

M

Polymer 
Manufacturing Processes 661 

molding or extrusion with the use of specially developed techniques and equipment to obtain 

accurate control of properties and shape. 

er carried 

hydroxyl 

STYRENE RESINS.30 Monomeric styrene (Chap. 36) is made by the pyrolysis-dehydrogenation of ethylbenzene, which is synthesized from ethylene and benzene. The factors that affect 

polymerization of the monomer are the temperature and purity of the styrene. Polymerization at moderate temperatures without catalysts produces resins of high average molecular 

weight, which impart high viscosity to their solutions. If the temperature is increased and 

catalysts such as benzoyl peroxide, oxygen, or stannic chloride are added, the average molecular weight and viscosity tend to decrease. Styrene of 99.5% purity, when heated to 80 to 

85°C in a stainless-steel kettle, polymerizes to a 35 or 40 percent conversion in 40 to 60 h. 

The viscous solution is passed down a tower, with zones of increasing temperature up to 

200°C, to strip off the unconverted monomer and to take off the polymer in a molten state. 

The extruded product is cooled and granulated. A blend of acrylonitrile-butadiene rubber 

with acrylonitrile-styrene resins produces ABS plastics. 

Another variation of polystyrene is a recently introduced poly p-methyl styrene, PMS. The 

p-methyl styrene is prepared from toluene and ethylene, and it is claimed that this is cheaper 

to produce than styrene. Superior properties are another plus for the PMS over polystyrene31. 

ACRYLIC RESINS AND PLASTICS." The methyl, ethyl, and butyl esters of acrylic and methacrylic acids are polymerized under the influence of heat, light, and peroxides. The polymerization reaction is exothermic and may be carried out in bulk for castings, or by emulsion, 

or in solution. The molecular weight decreases as the temperature and catalyst concentration 

are increased. The polymers are noncrystalline and thus very clear. Such resins are widely 

used because of their clarity, brilliance, ease of forming, and light weight. They have excellent optical properties and are used for camera, instrument, and spectacle lenses. Because of 

their excellent dielectric strength they are often used for high-voltage line spacers and cable 

clamps. Emulsions are widely applied as textile finishes and paints. 

ited 

Alloying and Blending33 

The properties of many plastics can be greatly modified by blending or alloying two or more 

polymers. The terms are often used interchangeably, but technically, blends are mixtures that 

are not fully compatible, and alloys are mixtures that are fully compatible such as polyethylene oxide and polystyrene. The blends appear as separate phases when viewed under a 

microscope. These combinations are taking over an increasing share of the market because it 

is much easier to develop desirable properties by mixing known plastics than by creating new 

ones. 

One of the problems associated with blends and alloys is how to make the components 

adhere together. One approach is to introduce a compatibilizer which creates interpenetrating polymer networks by providing a physical link between semicompatible materials. Most 

compatibilizers are block copolymers and they produce an interwoven matrix of physically 

MMod. Plast. 52 (6) 16 (1975); Hydrocarbon Process. 58 (9) 185 (1979); MPE, 1981-1982. 

31A Better Styrene Goes Commercial, Chem. Week. 130 (7) 42 (1982). 

32DuBois and John, Plastics, 6th ed., Van Nostrand Reinhold, New York, 1981. 

M

Polymer Alloys, Chem. Week 132 (9) 72 (1983). 
Klaus Weissermel 

Hans-Jiirgen Arpe 

Industrial 

Organic Chemistry 

Important 

Raw Materials and 

Intermediates 

Translated by 

Alexander Mullen 

Verlag Chemie • Weinheim • New York 

1978 
«fe: .«. 

Prof. Dr. Klaus Weissermel 

Dr. Hans-Jiirgen Arpe 

Hoechst AG 

Postfach 8003 20 

D-6230 Frankfurt SO 

West Germany 

Preface 

Copy Editing: Dr. Hans F. Ebel 

This book contains 43 Tables 

CIP-Kurztilefaufnahnie der Deutsche:n Bibliothek 

Weissermel, Klaus 

Industrial organic chemistry: important raw 

materials and intermediates / Klaus Weissermel; 

Hans-Jiirgen Arpe. - 1. Aufl. - Weinheim. New York: Verlag Chemie. 1978. 

Dt. Ausg. u.d.T.: Weissermel. Klaus: Industrielleorganische Chemie. 

ISBN 3-527-25706-3 (Weinheim) 

ISBN 0-89573-005-7 (New York) 

NE: Arpe. Hans-Jurgen: 

© Verlag Chemie GmbH. D-6940 Weinheim, 1978 

All rights reserved (including those of translation into foreign languages). No part of this book may be reproduced in 

.mv form - by photoprint, microfilm, or any other means - nor transmitted or translated into a machine language 

without written permission from ihe publishers. 

Registered names, trademarks, nc. used in this book, eir«nvirt».>Ht specific indication thereof, are not to be considered 

unprotected by law. 

Printer: Passavia Druckerei GmbH Passau 

Printed in West Germany 

Industrial organic cl 

as well as, to an ine 

present status of kn 

There was thus a an 

and intermediates < 

and to present it in : 

development, whict 

from their industrial 

ing discussions with 

This book addresse 

from it the chemisti 

manufacturing proc 

glean information a 

ami feedstocks alor 

disciplines in rho d 

economists - will b 

economic interrelat 

This book is arrang 

their tightest possib 

unavoidable. The ii 

As a rule, the manu 

merit and significa 

appficaitons of the p 

products' art" r'requ* 

existing technologic 

more, economic or r 

The authors endeav 

information are at t 

1. The main text. 

2. The synopsis of t 

3. Flow diagrams il 

These three typeso 

or making brief no 

notes which briefly 

to be rapidly inforn 
I0--U^o\^ry^ CGy&Z-' 

9.1. Vinyl-Halogen Compounds 197 

ch, 

W. 

With ethane, however, the involved technology for circulating 

the catalyst melt has only been employed in a pilot plant up to 

now {c.f. CH4 Oxychlorination, Section 2.3.6.1). 

inof 

<ystin-

>nie. 

ble 

:of 

led 

ra-

*as 

ith 

mg 

inIn 

na 

-n. 

9.1.1.4. Vinyl Chloride Applications 

In quantitative terms, vinyl chloride is chiefly employed as a 

monomer and comonomer in polymerizations. Only a minor 

amount, along with its precursor EDC, serves as starting material for numerous chlorine derivatives of ethane and ethylene 

for application as solvents and extractants. These compounds 

used to be solely derived from acetylene. 

1,2-Dichloroethane is also used as solvent for resins, asphalt, 

bitumen and rubber as well as extractant for fats and oils. 

Combined with tetraethyl- or tetramethyllead it serves in antiknock agents to convert almost non-volatile lead compounds 

into readily volatile ones. 

Furthermore, vinyl chloride and 1,2-dichloroethane are starting materials for the manufacture of vinylidene chloride {c.f. 

Section 9.1.2) and tri- and tetrachloroethylene {c.f. Section 

9.1.4). 

9.1.2. Vinylidene Chloride 

Vinylidene chloride (more properly named vinylidene dichloride, VDC) is manufactured by initially chlorinating vinyl 

chloride or 1,2-dichloroethane to 1,1,2-trichloroethane which 

is then dehydrochlorinated with aqueous Ca(OH)2 or NaOH at 

approx. 100 °C to VDC: 

applications of VCM: 

I. PVC and numerous copolymers 

main application areas for PVC: 

building and electrical industries, 

automobile construction 

2. intermediate products (also EDC) for 

manufacture of solvents and extractants, 

'gCljC-CHj (methylchloroform) 

C12C = CHC1 (trichloroethylene) 

CI2C = CC12 (tetrachloroethylene) 

and the monomer H2C - CCI2 

(vinylidene chloride, VDC) 

vinylidene chloride manufacture (twostep): 

1. conversion of VCM or 1,2-dichloroethane into 1,1,2-trichloroethane 

2. dehydrochlorination with aqueous alkali 

ess 

:he 

5) 

he 

H,C«CHC1 -^Cl* -

C1CH,-CH»CI + Cit ; 

ClCHjCHCH 

'fO 0) 

-*- H,C-CC1 , 

Vinylidene chloride can be readily copolymerized with vinyl 

chloride and other monomers. The polymers are used to coat 

cellulose hydrate films and polypropene in order to reduce air 

and water permeability. 

applications of vinylidene chloride: 

as comonomer with VCM (85% VDC + 

IS % VCM, 'Saran') for coating of films (cellulose hydrate and polypropene), with AN 

(30% VDC + 70% AN) for flame resistant 

acrylic fibers 
P.43 

I OIHI 

. V 

York 

York 

RGER 

keley 

^^^^| 

KIRK-OTHMER I 

ENCYCLOPEDIA OF 1 

CHEMICAL TECHNOLOGY I 

THIRD EDITION 1 

^M 

A WILEY-INTERSCIENCE PUBUCATION 

John Wiley & Sons 

NEW YORK • CHICHESTER • BRISBANE • TORONTO 
I 

••*«* » 

Copyright © 1978 bv John Wiley & Sons, Inc. 

All rights reserved. Published simultaneously in Canada. 

No pan of this book may be reproduced by any means, 

nor transmitted, nor translated into a machine language 

without the written permission of the publisher. 

Library of Congress Cataloging in Publication Data: 

Main entry under title: 

Encyclopedia of chemical technology. 

At head of title: Kirk-Othmer. 

"A Wiley-lnterscience publication." 

.Includes bibliographies. 

1. Chemistry, Technical-Dictionaries. I. Kirk, 

Raymond Eller, 1890-1957. II. Othmer, Donald Frederick, 

1904- III. Grayson, Martin. IV. Eckroth, David. 

V. Title: Kirk-Othmer encyclopedia of chemical technology. 

TP9.E685 1978 660' .03 

ISBN 0-471-02037-0 

77-15820 

Page 

{ Vlll 

I IX 

i XXI 

XXVI 

XXVIII 

XXIX 

120 

120 

120 

120 

120 

! 1 0 

120 

no 

623 

523 

624 

733 

932 

962 

Line 

Printed in the United States of America 
i>. v k 

764 VINYUDENE CHLORIDE AND PVDC 

VINYLIDENE CHLORIDE AND POLY(VINYLIDENE CHLORIDE) 

The most valuable property of poly (vinylidene chloride) [9002-85-1] (PVDC) 

and its copolymers is low permeability to a wide range of gases and vapors. The most 

serious deficiency is thermal instability at melt-processing temperatures. The techniques used to overcom$(i^y&taT&liTy7ft> copolymerization and plasticization, were 

developed at The Dow Chemical Company during the 1930s (1). The commercialization 

of these polymers under the trade name Saran began in 1939. 

In the United States, Saran is a generic term for high VDC-content polymers. 

(A letter following the name is used by Dow to indicate the type of comonomer, eg, 

Saran A for the homopolymer, B for copolymers with vinyl chloride (VC), and F for 

copolymers with acrylonitrile (AN).) In other countries, Saran is still a trademark of 

The Dow Chemical Company. The synonymous use of poly(vinylidene chloride) and 

Saran has resulted in many materials being identified in the literature as poly(vinylidene chloride) that were actually copolymers of unknown composition. Although it 

haa valuable properties, the homopolymer has not been used to any extent because 

of its difficult fabrication. Of the many copolymers that have been prepared, only three 

types are commercially important: vinylidene chloride-vinyl chloride copolymers 

[9011-06-7], vinylidene chloride-alkyl acrylate and methacrylate copolymers, and 

vinylidene chloride-acrylonitrile copolymers [9010-76-8] and methacrylonitrile copolymers [9010-80-4]. The literature on vinylidene chloride polymers through 1972 

is reviewed in ref. 2. Older reviews may also be of interest (3-4). 

Vinylidene Chloride 

Properties. Pure vinylidene chloride [75-35-4] (1,1-dichloroethylene) is a colorless, 

mobile liquid with a characteristic sweet odor. Its properties are summarized in Table 

1. Vinylidene chloride is soluble in most polar and nonpolar organic solvents. Its solubility in water (0.25 wt %) is nearly independent of temperature at 16-90°C. 

Manufacture. Vinylidene chloride monomer can be conveniently prepared in the 

laboratory by the reaction of 1,1,2-trichloroethane with aqueous alkali: 

2 CH2ClCHCla + Ca(OH)-, • 

90"C 

-*• 2 CH2=CC12 + CaCla + 2 H2 0 

Other methods are based on bromochloroethane, trichloroethyl acetate, tetrachloroethane, and catalytic cracking of trichloroethane (7). Catalytic processes produce 

by-product HCl rather than less valuable salts, but yields of vinylidene chloride have 

been too low for commercial use of these processes. However, good results have been 

reported with metal salt catalysts (8-10). 

Vinylidene chloride is prepared commercially by the dehydrochlorination of 

1,1,2-trichloroethane with lime or caustic in slight excess (2-10%) (6,11). A continuous 

liquid-phase reaction at 98-99°C yields ca 90% VDC. Caustic gives better results than 

lime. Vinylidene chloride is purified by washing with water, drying, and fractional 

distillation. It forms an azeotrope with 6 wt % methanol (12). Purification can be by 

distillation of the azeotrope followed by extraction of the methanol with water; an 

inhibitor is usually added at this point. Commercial grades contain 200 ppm of the 

monomethyl ether of hydroquinone (MEHQ). Many other inhibitors for the polymerization of vinylidene chloride have been described in patents, but MEHQ is the 
P.46 

766 VINYLIDENE CHLORIDE AND PVDC 

one most often used. The inhibitor can be removed by distillation or by washing with 

25 wt % aqueous caustic under an inert atmosphere at low temperatures. 

For many polymerizations, MEHQ need not be removed; instead, polymerization 

initiators are added. Vinylidene chloride from which the inhibitor has been removed 

should be refrigeruted at — 10°C, under u nitrogen ulmospherc, in tlie clurk, und in n 

nickel or baked phenolic-lined storage tank. If not used within one day, it should be 

reinhibited. 

Laboratory Polymerization. Vinylidene chloride polymerizes by both ionic and 

free-radical reactions. Processes based on the latter are far more common (13). Vinylidene chloride is of average reactivity when compared with other unsaturated 

monomers. The chlorine substituents stabilize radicals in the intermediate state of 

an addition reaction. Since they are also strongly electron withdrawing, they polarize 

the double bond, making it susceptible to anionic attack. For the same reason, a carbonium ion intermediate is not favored. 

The 1,1-disubstitution of chlorine atoms causes steric interactions in the polymer 

as is evident from the heat of polymerization (see Table 1) (14). When corrected for 

the heat of fusion, it is significantly less than the theoretical value of -83.7 kJ/mol 

(—20 kcal/mol) for the process of converting a double bond to two single bonds. The 

steric strain apparently is not important in the addition step, because VDC polymerizes 

easily. Nor is it sufficient to favor depolymerization; the estimated ceiling temperature 

for PVDC is ca 400°C. 

Homopolymerization. The free-radical polymerization of VDC has been carried 

out by solution, slurry; suspension, and emulsion methods. 

Solution polymerization in a medium that dissolves both monomer and polymer 

has been investigated (15). The kinetic measurements lead to activation energies and 

frequency factors in the normal range for free-radical polymerizations of olefinic 

monomers. The kinetic behavior of VDC is abnormal when the polymerization is 

heterogeneous (16). Slurry polymerizations are usually used only at the laboratory 

level. They can be carried out in bulk or in common solvents, eg, benzene. Poly(vinylidene chloride) is insoluble in these media and separates from the liquid phase as 

a crystalline powder. The heterogeneity of the reaction makes stirring and heat transfer 

difficult; consequently, these reactions cannot be easily controlled on a large scale. 

Aqueous emulsion or suspension reactions are preferred for large-scale operations. 

Slurry reactions are usually initiated by the thermal decomposition of organic peroxides or azo compounds. Purely thermal initiation can occur, but rates are very slow 

(17). 

The spontaneous polymerization of VDC, so often observed when the monomer 

is stored at room temperature, is caused by peroxides formed from the reaction of VDC 

with oxygen. Very pure monomer does not polymerize under these conditions. Irradiation by either uv or gamma rays (16,18) also induces polymerization of VDC. 

The heterogeneous nature of the bulk polymerization of VDC is apparent from 

the rapid development of turbidity in the reaction medium following initiation. The 

turbidity results from the presence of minute PVDC crystals. As the reaction progresses, the crystalline phase grows and the liquid phase diminishes. Eventually, a 

point is reached where the liquid slurry solidifies into a solid mass. A typical conversion-time curve is shown in Figure 1 for a benzoyl-peroxide-catalyzed mass polymerization (19). The first stage of the reaction is characterized by rapidly increasing rate, 

which levels off in the second stage to a fairly constant value; this is often called the